Organic light emitting devices are based on the principle that an organic light emitting layer is disposed between two electrodes, wherein one of the electrodes is at least partly transparent so that light can be emitted. By using an electrode with high transparency, high emission and hence high efficiency can be achieved. Currently, development is focused on transparent organic light emitting devices (OLEDs), where both electrodes are at least partly transparent. Therefore, transparent OLED devices are emissive in both the frontside and backside simultaneously. For several applications, it may be desired to have emission in both directions. However, for other applications it would be preferred to control the emission directions. For example, it may be advantageous to have a high transparency combined with reduced or even no emission from the backside and good emission from the front of the light emitting device.
In WO2010/046833A an OLED is described comprising an organic layer between an anode and a cathode, and a mirror layer on the anode or the cathode, wherein the mirror layer is structured into nontransparent zones and transparent zones. The OLED can be completely or partly deactivated in the transparent zones. By this structure the OLED can be made transparent for light and simultaneously the emission can be controlled to a certain degree. The non-transparent mirror zones block light emission and reflect light into the desired direction.
However, there is still a need in the art for solutions that provide improved emission control of transparent light emitting devices.